Summer Chinook Returns at Bonneville Dam Exceed 10-Year Average

Over 67,000 summer chinook were counted passing the Bonneville Dam between June 16th and July 31st, beating the 10-year average for the same time period by 24,000.

Photo courtesy: valleywater.org

(PORTLAND) - The number of returning summer chinook salmon greatly exceeded the 10-year average according to the federal agencies responsible for salmon recovery efforts in the Federal Columbia River Hydro System.

The summer chinook return follows a healthy spring chinook return that ended June 15th. Even though the spring return of over 126,000 was slightly below the 10-year average, it was still better than any spring chinook return during the 1980s and 1990s.

“This year’s spring and summer chinook salmon return is further evidence that the region’s efforts are making a difference.

In particular, the improvements in the swift and safe passage of juvenile salmon through the dams are helping salmon recovery for the long term,” said Bob Lohn, head of the Northwest region of the National Oceanic and Atmospheric Administration’s fisheries service.

The federal agencies continue to look at new ways to improve both juvenile and adult salmon migration and to monitor the effectiveness of measures such as spilling additional water over the dams and barging juvenile salmon.

Because the benefits of this additional spill are still uncertain, the U.S. Army Corps of Engineers is conducting a number of studies during the spill to determine how best to operate the dams in a manner that aids fish survival.

For example, this summer, under the second consecutive year of court-ordered operations, federal dam operators are spilling additional water at the four Lower Snake River dams and McNary Dam on the Columbia River.

Lohn emphasized that even though the 10-year average for returning chinook is going up, the salmon runs are variable and that improved in-river conditions for juveniles do not always translate into larger adult returns because the ocean plays an even greater role than the river in adult salmon returns.